Clamp structures provided with so-called "Oetiker" ears have enjoyed enormous commercial success over the past several decades. These clamp structures may be two-ear clamp structures made from tubular stock, as shown in my prior U.S. Pat. No. 2,614,304, one-ear clamp structures made from tubular stock as shown in my prior U.S. Pat. No. 3,082,498, open clamp structures adapted to be interconnected by a bridging portion provided with an "Oetiker" ear as shown in my prior U.S. Pat. No. 2,847,742, or open clamp structures provided with mechanical interconnecting means as disclosed in my prior U.S. Pat. Nos. 3,475,793; 3,523,337; 4,103,399 and 4,237,584. Whereas the holding ability of open-type clamp structures depends both on the mechanical interconnection of the open ends of the clamping band as well as on the holding ability of the ear, the holding ability of the clamp structures made from tubular stock such as shown in my prior U.S. Pat. No. 2,614,304, apart from strength considerations of the clamping band, depends on the holding ability of the plastically deformable "Oetiker" ear. This, in turn, depends on the type of material and thickness of the clamping band as well as on the design of the ear itself. Efforts to increase the holding ability of such clamp structures by the use of reinforcing grooves, as disclosed in my prior U.S. Pat. No. 3,402,436 and in my copending U.S. application Ser. Nos. 06/922,408 and 06/922,473, filed Oct. 22, 1986 and Oct. 23, 1986, respectively have greatly increased the holding ability of clamp structures. However, in some applications, it is desirable to still further increase the holding ability of the clamp structure, i.e., the force with which the clamp structure can be closed so as to avoid leakages in the event of changes in temperature and/or pressure of the fluid carried by the hose which is secured by the clamp structure, for example, on a nipple. The ability of the clamp structures with so-called "Oetiker" ears to compensate for changes in temperature and/or pressure by the residual elasticity in the plastically deformed ear is one of the important advantages obtainable with the clamp structures disclosed in my prior patents. However, the desire to increase the holding ability while maintaining effective automatic compensation for temperature and/or pressure is a requirement that is fraught with some contradiction. My prior Swiss Patent 580,247 disclosed an arrangement pursuant to which the plastically deformed ear can be subjected only to a predetermined maximum reopening force. However, the force required for reopening the ear up to its maximum limit is unaffected by this arrangement.
The U.S. Pat. 3,087,221 proposed a hose clamp in which the clamping band had its greatest radial thickness near its middle with the thickness progressively reduced towards its ends in order to maintain a true circle initially and upon change of diameter. In FIG. 3 of this patent, the ear itself was also proposed to be made in the same manner as the clamping band, i.e., having its greatest thickness in the middle with reduced thickness toward the ends of the ear. Apart from a lack of disclosure of how the clamps as proposed in this patent can be realized in practice, this patent was concerned only with maintaining a true circular configuration of the parts in question.
The European Patent 0 280 598 discloses an arrangement for a clamp structure provided with an outwardly extending circular fold or loop in the clamping band in which the elasticity reserve is to be determined by a slotted sleeve surrounding the fold or loop. However, this patent is concerned with limiting the elasticity reserve in a fold or loop of the type shown in FIG. 1 in my prior U.S. Pat. No. 3,475,793 in which bent-out lugs or folds 2 constitute tensional spring elements. Thus, according to this European patent, the tensional spring reserve of such folds made from intentionally elastic spring steel material is to be limited by the use of the sleeve, whereas the present invention is concerned with problems arising out of the use of so-called "Oetiker" ears made from plastically deformable band material.